High rates of failed reunification indicate that family preservation (FP) does not necessarily lead to permanency for children. It could be argued that, in such failed cases, the decision-making process leading to the preservation of the family was inadequate. In order to gain insight into the role that decision-making plays in family preservation practice, we studied decision-making within an FP-intervention program provided by the Expertise Center. The Expertise Center explicitly combines treatment and decision-making in an assessment-based intervention that is provided to families seeking either to be reunited with their young child (0–2) or to avoid an out-of-home placement of the child. In addition, at least one of the parents has psychiatric problems. We hereby attempted to a) map decision-making trajectories in practice and b) provide feedback about Expertise Center decision-making based on evidence regarding the – sometimes evolving – quality of parental behavior as observed in the participants. We have used a descriptive design (n = 100) as well as a one-group repeated measures design (n = 28) to examine parental behavior using the Atypical Maternal Behavior Instrument for Assessment and Classification (AMBIANCE). We hypothesized that a negative recommendation regarding family preservation would manifest itself in the display of more frequent and more severe atypical parental behavior. Our results indicate that the Expertise Center succeeded in contributing broadly to timely decision-making in the context of permanency planning, and that implementation of the Decision-making Continuum potentially improved the quality of clinical decision-making. Furthermore, our hypothesis was confirmed by four out of five measurements of parental behavior that have been proven to be significant for children's attachment security. Since these are promising results, the Expertise Center program could serve as an inspiration for the practice field.